Mysterious Ice Formation

November 2, 2003 In February of 2002, my father-in-law, John Rohner, sent me photos of a mysterious ice formation he had seen at his home in Asheville, NC. He asked me to show them to any snow and ice experts I might know, to ask how this ice might have formed. It's taken me a while, but I've finally gotten them scanned and posted. Here's John's note to me:

"Photos taken at 9 a.m. 27 Jan 2002, at [our home in Asheville]. Water frozen in a bird bath approx 1 1/2" deep. The ice formation as pictured was 7" long. No foreign matter in the ice formation. No branches overhead. No rain or wind during the night. Low temp at night of 26 Jan was 24 degrees [F]. The bird bath is made of glazed pottery, had been reglued after a break 2 years before. Area where glued was coated with transparent silicone caulk. This was done also 2 years ago. Note the lateral bubbles in the ice formation."

He also made a sketch of a cross-section of the column. (Click on any of the thumbnails for a larger image.)